Polygonal driving means with inbuilt collar

ABSTRACT

It has become apparent that the dimensions of inbuilt-collar driving means of the same nominal size may vary according to the method of manufacture. The dimensions of the collar must therefore be adapted to suit the mode of manufacture, at the expense of its strength or mass. Moreover, the transmissible torque for tightening and loosening operations varies according to a useful wrenching height. In order to have a useful height identical to the height of the shank ( 7 ), the idea underlying the invention involves pushing the frustoconical collar ( 152 ) of a driving means ( 151 ) in towards its center along the extension of the sides of the shank. The inbuilt-collar driving means proposed by the invention is suited to all modes of manufacture, and can be manufactured without adversely affecting the dimensions of the driving means or its installation.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. application Ser. No. 13/125,081, filed Jun.6, 2011, patented, which is a Section 371 application ofPCT/FR2009/051990 filed Oct. 19, 2009, which claims priority from FrenchPatent Application Number 0857127 filed Oct. 20, 2008 and French PatentApplication Number 0951378 filed Mar. 4, 2009, each of which isincorporated by reference herein in their entirety.

BACKGROUND

This invention relates to a polygonal driving means with an inbuiltcollar and fitted with socket faces. The technical field of theinvention relates, in a general manner, to that of driving means. Moreparticularly, the invention relates to nuts and screws with inbuiltfrustoconical-type collars.

In the prior art, the teaching particularly of model USD206402 is knownand describes a reinforced nut with a frustoconical collar, representedin a schematic manner in FIGS. 1A and 1B.

FIG. 1A represents a front view of such a nut 1 and FIG. 1B represents aside view with a partial cross-section of the same nut 1. Thecross-section is defined by planes 1B-1B. The nut 1 comprises a shank 2and a frustoconical collar 3. A cylindrical inner wall 4 of the nut 1 isthreaded and may have a recess. Six buttresses 5 connect the collar 3 tothe shank 2.

In the prior art, non-reinforced nuts with frustoconical collars arealso known, such as those represented in FIGS. 2A and 2B. The same typesof geometries are found with regard to the screw heads.

FIG. 2A represents in a schematic manner an oblique perspective view ofan example of a forged nut 5 with a frustoconical collar 6. A junctionbetween a hexagonal shank 7 and the frustoconical collar 6 of the forgednut 5 comprises a fillet present in the form of an elliptical rim 8. Acircular base 9 of the cone of the collar 6 extends into a cylinder 10.When a wrench socket, not represented, is threaded around the shank 7,one end of the socket abuts against the elliptical rim 8. A height 11,separating a crest 12 of the elliptical rim from an upper surface 13 ofthe forged nut 5, is effectively in contact with the wrench socketduring a tightening or loosening operation of the forged nut 5; this isthe wrenching height or useful height 11. The cylindrical inner wall 4of the forged nut 5 is threaded and may have a recess.

FIG. 2B represents in a schematic manner an oblique perspective view ofan example of a machined nut 14 with a frustoconical collar 15. Ajunction 16 between a hexagonal shank 17 and the frustoconical collar 15of the machined nut 14 is machined so as to form a fin and so that theshank 17 has perfectly rectangular sides. A circular base 18 of the coneof the collar 15 extends into a cylinder 19. When a wrench socket, notrepresented, is threaded around the shank 17, one end of the socketabuts against the junctions 16. A useful height 20, separating ajunction 16 from an upper surface 21 of the machined nut 14, iseffectively in contact with the wrench socket during a tightening orloosening operation of the machined nut 14. The cylindrical inner wall 4of the machined nut 14 is threaded and may have a recess.

For nuts with identical dimensions, the useful height 11 of the forgednut 5 is therefore shallower than the useful height 20 of the machinednut 14. Due to the elliptical rims 8, the support surface with theappropriate wrench socket is less significant, which reduces thetransmissible torque.

FIG. 2C schematically represents a side view of half of a forged nut 5with a frustoconical collar 6 and half of a machined nut 14 with afrustoconical collar 15 from the prior art. This figure shows, for thesame overall height 22, collars 15 and 6 to be different and thewrenching height 20 to be identical. In particular, the cylindrical part10 is shallower than the cylindrical part 19.

FIG. 2D schematically represents a side view of half of a forged nut 5with a frustoconical collar 6 and half of a machined nut 14 with afrustoconical collar 15 from the prior art. This figure shows collars 15and 6 to be identical and the wrenching height 11 of the forged nut 5 tobe shallower than that 20 of the machined nut 14.

It has become apparent that the dimensions of the collar nuts of thesame nominal size, i.e. of the same inner threading, may vary accordingto the method of manufacture. This also applies for all driving meanssuch as screw heads. This is why, in the following text, it must beremembered that the invention relates to all driving means with aninbuilt collar.

It is initially advised that, if the useful wrenching height is to bekept the same for both a forged driving means and a machined drivingmeans, the height of the shank must be increased by a length equal tothe height of a rim, the total height of the driving means thereforebeing increased to the same extent.

This heterogeneity of shank heights for driving means intended for thesame use is a source of numerous technical problems.

Indeed, as the shank height of a forged driving means is greater thanthat of a shank of a machined driving means, the forged driving meanshave a greater volume, therefore a greater mass and more material, whichis problematic and costly with regard to their storage, transport anduse, in particular in aircraft.

If, on the other hand, the height of the collar is reduced, thisreduction is detrimental to the mechanical aspect, i.e. the strength ofthe collar.

Finally, as the forged driving means are generally produced in largequantities compared to the machined driving means, the aforementionedproblems are all the more incapacitating.

On the machined version, numerous fins can be observed in a transitionzone between the hexagonal socket faces and the collar. These finsoriginating from the machining process are not suited to forging.Indeed, identical angular shapes cannot be forged as this createsmaterial filling problems. Furthermore, for the forged version,elliptical fillets replace the machining fins to ease the filling of adie with the chosen material such as a titanium alloy, stainless steel,nickel alloy or even an aluminium alloy.

It therefore follows that, for the same wrenching height and the sameheight of the driving means, the machined driving means and the forgeddriving means do not have the same collar height. The collar strength istherefore weaker on a forged driving means.

In order to produce equal levels of strength between the machined collarand the forged collar, either the height of the forged driving meansmust be increased, which has the disadvantage of making it heavier thanthe machined driving means, or the wrenching height reduced, whichreduces the transmissible torque for tightening and looseningoperations.

SUMMARY

The inbuilt-collar solution proposed by the invention is suited to allmodes of manufacture such as machining, forging, sintering, casting andplastic injection moulding, and can be manufactured without adverselyaffecting the dimensions of the driving means, its strength or its modeof installation.

The main modification was provided to the collar, where a recess at thebottom of each socket face avoids the need for elliptical rims producedby the forging method.

Fillets are fitted between the socket faces and the sides of thehexagonal shank of the driving means, preferably rays or ellipses or anyother form providing for a good flow of material during forging.

In the prior art, during a screwing or unscrewing operation of a drivingmeans using a power tool, the rotation speed of the driving means leadsto a significant increase in the temperature of the driving means, viafriction.

This raised temperature is the source of various technical problems:

-   -   the operator may burn himself/herself while manually holding the        screw or nut,    -   the material on which the screwing operation is performed may        become damaged and deformed, above all if this is made out of        composite material such as that used in aeronautics,    -   the coating, for example anticorrosion and/or lubricating        coating, covering the screw or nut, may become deteriorated,        which is detrimental to its efficiency,    -   the braking system, applied to some nuts to prevent them from        loosening once fitted, may become degraded.

The invention has numerous advantages.

A recess made at the bottom of each socket face leads to a reduction inthe mass of the driving means. This recess does not affect themechanical strength of the driving means, as the hollowed out area issubject to very little mechanical stress. Ideally, a driving means suchas that represented in FIG. 10 corresponds to a maximal recess in termsof mass.

The design is universal, thus making all modes of manufacture possiblewithout requiring major dimensional changes. The wrenching height nolonger poses a problem and the mass remains identical.

A single-shaped driving means of the same nominal size, for whatevermethod of manufacture, enables the driving means and its height to bemore easily recognised visually.

The star-shaped recesses produced on the collar can take severaldifferent shapes, as represented in FIGS. 3 to 10. Moreover, this typeof solution can be applied to a bi-hexagonal driving means.

The inbuilt collar according to the invention, due to its reduced massvia recesses in the material, has increased thermal diffusionproperties, which reduces the amplitude and duration of the temperaturerise of the driving means during screwing and/or unscrewing operations,and resolves at least in part the aforementioned problems.

Thus, the idea underlying the invention involves deleting the ellipticalrims 8 in order to create a useful height identical to the height of theshank. In order to achieve this, the frustoconical collar is pushed intowards its center along the extension of the sides of the shank.

Via this invention, the same dimensions are obtained for driving meansin machined mode and forged mode, leading to an identical mass and thesame wrenching heights and therefore to identical transmissible torques.

The star-shaped collar solution proposed overcomes the restrictionsrelated to the method of manufacture with regard to the dimensions ofthe driving means, and produces a reduction in mass with identicalstrength and wrenching heights. The star shape enables a moresignificant tightening and loosening torque to be transmitted by using atool adapted to suit this shape.

The socket faces generated by the invention allow for the simpleproduction of different colorings or markings such as the part referencenumber, a diameter marker or the material used, which up to now havebeen difficult to produce on a driving means with a classic collar.

The invention therefore relates to a polygonal driving means with aninbuilt collar, obtained by forging via a die or by machining,characterised in that the collar comprises socket faces, hollowed outwith regard to a collar surface and aligned with the lateral sides ofthe driving means.

The invention also relates to a cylindrical tightening and looseningwrench socket for a polygonal driving means according to the invention,the wrench socket comprising a cavity with a polygonal hollow shank andan end fitted so as to be abutted against an inbuilt collar of thedriving means, the end of the wrench socket having sides with shapescomplementing those of the collar so as to be pressed against the latterduring the abutment, characterised in that the collar comprises socketfaces hollowed out with regard to a collar surface and aligned with thelateral sides of a shank of the driving means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its different applications will be better understoodafter reading the following description and after examining theaccompanying figures. These are intended for purposes of illustrationonly and are not intended to limit the scope of the invention. Thefigures show:

FIG. 1A, previously described: a schematic representation of a frontview of an example of a reinforced nut from the prior art;

FIG. 1B, previously described: a schematic representation of a side viewwith a partial cross-section of the same example of a nut;

FIG. 2A, previously described: a schematic representation of an obliqueperspective view of an example of a forged nut with a frustoconicalcollar from the prior art;

FIG. 2B, previously described: a schematic representation of an obliqueperspective view of an example of a machined nut with a frustoconicalcollar from the prior art;

FIG. 2C, previously described: a schematic representation of a side viewof half of a forged nut with a frustoconical collar and half of amachined nut with a frustoconical collar from the prior art;

FIG. 2D, previously described: a schematic representation of a side viewof half of a forged nut with a frustoconical collar and half of amachined nut with a frustoconical collar from the prior art;

FIG. 3A: a schematic representation of an oblique perspective view of afirst example of a nut with a driving means with a frustoconical collaraccording to the invention,

FIG. 3B: a schematic representation of a side view of the first exampleof a nut with a driving means with a frustoconical collar according tothe invention;

FIG. 4: a schematic representation of an oblique perspective view of asecond example of a nut with a driving means according to the invention;

FIG. 5: a schematic representation of an oblique perspective view of athird example of a nut with a driving means according to the invention;

FIG. 6: a schematic representation of an oblique perspective view of afourth example of a nut with a driving means according to the invention;

FIG. 7: a schematic representation of an oblique perspective view of afifth example of a nut with a driving means according to the invention;

FIG. 8: a schematic representation of an oblique perspective view of asixth example of a nut with a driving means according to the invention;

FIG. 9: a schematic representation of an oblique perspective view of aseventh example of a nut with a driving means according to theinvention;

FIG. 10: a schematic representation of an oblique perspective view of aminimised model of a nut with a driving means according to theinvention;

FIG. 11: a schematic representation of an oblique perspective view of awrench socket with a partial cross-section for the first example of adriving means according to the invention;

FIG. 12: a schematic representation of an oblique perspective view of aneighth example of a nut with a driving means according to the invention,fitted with a washer enabling swivelling; and

FIG. 13: a schematic representation of an oblique perspective view of anexample of a screw with a driving means according to the invention.

DETAILED DESCRIPTION

FIG. 3A represents, in a schematic manner, an oblique perspective viewof a first example of a nut with a driving means 23 with a frustoconicalcollar 6 according to the invention. In one example, the driving means23 and its embodiments represented in the following figures are obtainedby forging via a die. Alternatively, said driving means may also beobtained via another mode of manufacture such as, for example,machining, casting, plastic injection moulding and sintering, so as toproduce driving means with an identical use from whatever mode ofmanufacture. The driving means 23 comprises a polygonal shank, in thisexample hexagonal in shape 7 and a frustoconical collar 6. According tothe invention, the collar 6 is fitted with hollowed out socket faces 24.In the example given in FIG. 3, the socket faces 24 are planar.According to the invention, hollowed out means that a portion of theside is misaligned inwards with regard to the frustoconical curvedsurface. A circular base 18 of the cone of the collar 6 extends into acylinder 19. The driving means 23 comprises fillets 25 fitted betweenthe socket faces 24 and the flat lateral sides 70 of the shank 7. In apreferred example, the driving means 23 and its embodiments describedhereinafter are made out of a titanium alloy and covered with an organicresin-based coating containing polytetrafluoroethylene, also known asPTFE. Alternatively, this may be made out of stainless steel, a nickelalloy or an aluminium alloy. The cylindrical inner wall 4 of themachined driving means 23 is threaded and may have a recess.

FIG. 3B schematically represents a side view of the first example of anut with a driving means 23 with a frustoconical collar 6 according tothe invention. Typically, the frustoconical surface of the collar 6forms an angle of at least forty-five degrees with the plane of thecircular base 18 considered as being horizontal.

FIG. 4 schematically represents an oblique perspective view of a secondexample of a nut with a driving means 26 according to the invention. Inthis example, the driving means 26 comprises a hexagonal shank 7 and hasa hexagonal pyramidal collar 28. The planar socket faces 81 in thisexample make up the collar 28. A hexagonal base 51 of the pyramid of thecollar 28 extends into a parallelepiped 27. The driving means 26comprises fillets 29 fitted between the socket faces 81 of the collar 28and its flat lateral sides 70. The cylindrical inner wall 4 of themachined driving means 26 is threaded and may have a recess.

FIG. 5 schematically represents an oblique perspective view of a thirdexample of a nut with a driving means 30 according to the invention. Inthis example, the driving means 30 comprises a hexagonal shank 7 and asemi-cylindrical 10, semi-frustoconical 50 collar and is fitted withsocket faces 31 with regard to the frustum. In this example, the socketfaces 31 are planar with significant inclines. More precisely, thesocket faces 31 intersect the cylinder 10 at a periphery of a lower side44 of the driving means 30. The socket faces 31 have elliptical segments45 and 46 at the junction with this cylinder 10. Two adjacent socketfaces 47 and 48, from all of the socket faces 31, therefore jointogether at the junction 49 between the two elliptical segments 45 and46. Rather than comprising a fin corresponding to the junction betweenthese two socket faces 47 and 48, the collar 10 comprises, at thisjunction, a portion of frustoconical connection surface 50, almosttriangular in shape, as its two longest sides 50.1 and 50.2 areelliptical with very little curvature. The driving means 30 comprisesfillets 32 fitted between the socket faces 31 and the flat lateral sides70. The cylindrical inner wall 4 of the machined driving means 30 isthreaded and may have a recess.

FIG. 6 schematically represents an oblique perspective view of a fourthexample of a nut with a driving means 33 according to the invention. Thedriving means 33 comprises a hexagonal shank 7 and a semi-frustoconical52, semi-rounded 53 collar fitted with socket faces 34 in the form oflugs. A circular base 56 of the cone of the rounded part 53 extends intoa thin cylinder 57. The socket faces 34 are planar. The driving means 33comprises fillets 35 fitted between the planar part 54 of the socketfaces 34 and the flat lateral sides 70. An upper part 54 of the socketfaces 34 intersects the frustoconical part 52 so as to leave one portionof frustoconical connection surface 52.1 only, almost trapezium in shapeas its two longest sides 52.2 and 52.3 are elliptical with very littlecurvature. The lower part 55 of the socket faces 34 intersects therounded part 53 and thus forms, at this junction, an elliptical segment58 with significant curvature, the crest 59 of which almost touches thecircular base 56. Alternatively, the socket face is parallel to a cone'sgenerator for the collar and thus forms, at the junction, tworectilinear segments. The cylindrical inner wall 4 of the machineddriving means 33 is threaded and may have a recess.

FIG. 7 schematically represents an oblique perspective view of a fifthexample of a nut with a driving means 36 according to the invention. Thedriving means 36 comprises a hexagonal shank 7 and a frustoconicalcollar 60 fitted with concave socket faces 37. A circular base 56 of thecone of the collar 60 extends into a thin cylinder 61. The socket faces37 intersect the frustoconical collar 60 and thus form, at thesejunctions, elliptical segments 62 and 67, the crests 63 and 68 of whichalmost touch the circular base 56. Two adjacent socket faces 64 and 65,from all of the socket faces 37, therefore join together at the junction66 between the two elliptical segments 62 and 67 and form a concave fin68 extending to a straight fin 69 separating two flat sides 70 and 71from the six sides of the hexagonal shank 7. The cylindrical inner wall4 of the machined driving means 36 is threaded and may have a recess.

FIG. 8 schematically represents an oblique perspective view of a sixthexample of a nut with a driving means 38 according to the invention. Thedriving means 38 comprises a hexagonal shank 7 and a frustoconicalcollar 72 fitted with concave socket faces 39. A circular base 73 of thecone of the collar 72 extends into a thin cylinder 74. The socket faces29 intersect the frustoconical collar 72 and thus form, at thesejunctions, hemispherical segments 75 and 76. Two adjacent socket faces77 and 78, from all of the socket faces 39, join together at a junctionpoint 87 between the two elliptical segments 75 and 76, said junctionpoint 87 being on the same axis as a straight fin 69 separating two flatsides 70 and 71 from the six sides of the hexagonal shank 7. A lowercrest 79 of the segment 75 almost touches the circular base 73. An uppercrest 87 of the segment 75 continuously joins the side 70; i.e. withouta fillet. The cylindrical inner wall 4 of the machined driving means 38is threaded and may have a recess.

FIG. 9 schematically represents an oblique perspective view of a seventhexample of a nut with a driving means 42 according to the invention. Thedriving means 42 comprises a bi-hexagonal shank 91 and a frustoconicalcollar 92 fitted with twelve socket faces 95 in furrows 102. The furrows102 separate the socket faces 95 into two sides 103 and 104. The sidesof the shank 91 have a cylindrical part 93 and a concave part 94. Thesocket faces 95 have a flat part 96 and a concave part 97. The socketfaces 95 intersect the frustoconical collar 92 and thus form, at thesejunctions, saw-toothed segments 98 and 99. Two adjacent socket faces 100and 101 from all of the socket faces 95 intersect the frustoconicalcollar 92 so as to leave a small connection part 93 and 94 only of thetwelve sides of the shank 91. The cylindrical inner wall 4 of themachined driving means 42 is threaded and may have a recess.

FIG. 10 schematically represents an oblique perspective view of aminimised model of a nut with a driving means 119 according to theinvention, corresponding to a maximal recess in the material, notadversely affecting the mechanical strength, with buttresses 88 and 89located on either side of the alignment of a side 70 of the shank 120,large in height compared to the previous embodiments of the drivingmeans. Buttresses 88 and 89 are present in the form of two thinright-angled triangles. The buttresses 88 and 89 are connected by theirlower base via a thin, flat hexagonal collar 90. The cylindrical innerwall 4 of the machined driving means 119 is threaded and may have arecess.

FIG. 11 schematically represents an oblique perspective view of a wrenchsocket 131 with a partial cross-section according to the invention. Thewrench socket 131 has a semi-frustoconical 132, semi-cylindrical 133outer shape. Such a wrench socket is intended for tightening andloosening operations for one of the driving means 23, 26, 30, 33, 36,38, 42, or 119 according to the invention, represented in the previousfigures. In this example, the wrench socket 131 comprises a cavity 134with a polygonal hollow shank 135, in this case hexagonal in shape, andan end 136 fitted so as to be abutted against the frustoconical collar 6of the driving means 23 represented in FIG. 3. The end 136 has two sides137 and 138 with shapes complementing those of the socket faces 24 andof the collar 6 of the driving means 23 so as to be pressed against themduring the abutment. Finally, the wrench socket 131 comprises a squarehollow shank 139 intended to accommodate one end of a tightening andloosening wrench, not represented.

FIG. 12 schematically represents an oblique perspective view of aneighth example of a nut with a driving means 140 according to theinvention, fitted with a washer 141 enabling swivelling, The drivingmeans 140 comprises a hexagonal shank 7 and a frustoconical collar 142fitted with socket faces 147, in this case planar in shape. The socketfaces 147 intersect the frustoconical collar 142. The cylindrical innerwall 4 of the machined nut 140 is threaded and may have a recess. Thecollar 142 has a spherical lower support surface 143, complemented andconnected, in the same way as a ball and socket joint, with the washer141 enabling swivelling. The washer 141 has a diameter greater than thatof the collar 142. In one example, the section of the washer 141 isrectangular or even square in shape, from which an inner corner 144 incontact with the lower side 143 of the collar 142 has been bevelled intoan arc of a circle. The washer 141 therefore has a concave housing 145in the shape of a portion of a sphere, so as to accommodate thespherical support collar 142. Therefore, when the driving means 140 isscrewed around a screw to tighten an element, an inner side 146, in thiscase flat in shape, of the inserted washer 141 is supported by saidelement, even if the screw axis is not perpendicular to the surface ofthe element being tightened in the tightening zone. The misalignment ofa central axis of the washer 141 with regard to the screwing axis canhave a value of more or less ten degrees.

FIG. 13 schematically represents an oblique perspective view of anexample of a screw 148 with a driving means according to the invention.The screw 148 comprises a shaft 149 of which at least one part 150 isthreaded, and a polygonal driving means 151 present in the form of ascrew head. The head 151 comprises a polygonal shank 7, in this casehexagonal in shape, and an inbuilt frustoconical collar 152 obtained byforging using a die or by machining. In order to optimise the wrenchingheight, according to the invention, the collar 152 comprises socketfaces 153, in this case planar in shape, aligned with the lateral sidesof the shank 7 of the head 151 of the screw 148. The socket faces 153intersect the frustoconical collar 152 and thus form, at thesejunctions, elliptical segments 154 and 155. A circular lower side 156 ofthe collar 152 is preferably flat so as to press against an elementbeing tightened. All of the profiles used for the driving means in FIGS.3 to 11 can also be used for the head 151 of the screw 148. A classicwasher or a washer such as that seen in the previous figure in the caseof a spherical support collar, can be inserted between the lower side156 and said element being tightened.

1. An assembly of a washer and a monolithic nut, wherein the monolithicnut comprises a polygonal shank with lateral sides and an inner wall onthe polygonal shank having cylindrical threads along the inner wall ofthe polygonal shank, the monolithic nut having a frustoconical collarhaving a spherical lower portion and a bottom surface wherein thethreads and the bottom surface are configured such that a threadingmovement of the nut along a mating threaded surface puts the sphericallower portion into contact with the washer, such that the contact placesan axial load on the spherical lower portion of the collar, anupper-most collar surface opposite the bottom surface and afrustoconical curved surface between the bottom surface and theupper-most collar surface, wherein the frustoconical collar comprises aplurality of socket faces hollowed out from and relative to thefrustoconical curved surface in an area between the bottom surface andthe upper-most collar surface and wherein the socket faces extend to aplane defined by the respective polygonal shank lateral side, eachlateral side of the polygonal shank being aligned with a respectivehollowed-out socket face, and each lateral side of the polygonal shankterminates at a substantially transverse surface between the lateralside and a respective hollowed-out socket face at the intersection ofthe upper-most collar surface and the polygonal shank.
 2. The assemblyof claim 1 wherein the socket faces are planar.
 3. The assembly of claim1 wherein the nut is obtained by forging via a die, machining, casting,sintering or plastic injection molding.
 4. The assembly of claim 1,further comprising fillets fitted between the socket faces of thefrustoconical collar and the lateral sides of the polygonal shank. 5.The assembly of claim 1 wherein the nut is made out of titanium alloy,stainless steel, nickel alloy or aluminium alloy.
 6. The assembly ofclaim 1, wherein the shank is hexagonal or bi-hexagonal.
 7. The assemblyof claim 6, wherein the frustoconical curved surface of thefrustoconical collar forms an angle of at least forty-five degrees witha circular base of the collar.
 8. The assembly of claim 1, wherein thesocket faces are marked or colored.